GLSP-1682: Add deprecation notices and disable auto-publish

[tortmayr]

What it does

All packages of this repository have been migrated to the consolidated
glsp-core monorepo. This PR marks the
repository as deprecated ahead of archival and stops it from publishing to npm.

• Add a deprecation banner to the root README.md and CONTRIBUTING.md, pointing
  contributors to glsp-core and to the GLSP umbrella repo for issues
• Add a deprecation block to all npm-visible package READMEs, naming the new
  location of each package in glsp-core — these ship in the npm tarballs and are
  the only notice a consumer sees on npmjs.com
• Note in the workflow-server-bundled-web README that the package is private in
  glsp-core and will no longer be published to npm
• Remove the workflow_run trigger from publish.yml. Without this, merging this
  very PR would trigger CI and in turn publish 2.9.0-next packages from here,
  racing the releases from glsp-core. workflow_dispatch/workflow_call are kept
  for manual emergency republishes.
• Mark the repository as deprecated in AGENTS.md and CLAUDE.md so coding agents
  do not implement changes here

ci.yml, e2e.yml and codeql-analysis.yml are left untouched — they have no
publish side effects and archiving disables Actions anyway.

Part of: eclipse-glsp/glsp#1682

How to test

Documentation and workflow metadata only, no build required.

• Verified the rendered banners in the GitHub preview of each README
• Verified publish.yml no longer has a workflow_run trigger, so no publish
  job is queued by CI runs on main

Follow-ups

• Archive the repository once this is merged
• The publish job's if condition and checkout ref still reference
  github.event.workflow_run.*. These are dead expressions for dispatch/call runs
  and were intentionally left in place to keep the diff minimal on a frozen repo.

Changelog

• This PR should be mentioned in the changelog
• This PR introduces a breaking change (if yes, provide more details below for the changelog and the migration guide)